Like his mother, when
Prince George wears an outfit it almost instantly sells out. So, when the tot arrived at the hospital to meet his newborn baby sister Princess Charlotte last month wear a navy blue knitted cardigan and knee-high socks by Amaia Kids, it's no surprise the company sold out online within hours.

The classic and traditional London-based childrenswear store has long been a favourite with George's mom
Kate Middleton and now the designer Amaia Arrieta is opening up exclusively to HELLO! US' sister publication ¡HOLA!about first meeting the Duchess, and her loyalty to the brand.

"The first time she came into the shop she was with her mother [
Carole Middleton]," Amaia, who is one half of the business with fellow mom Ségolène Tresca, told HOLA!. "It was quite funny because she said, 'I've just had a baby and I'm a little lost. Would you be able to help me?' Of course we knew who she was! It surprised us to see how normal and natural she was. We helped her like any new mom and I think she liked that because she's been coming back ever since."

"She's very charming, very normal and very sweet," said the designer of Duchess Kate Photo: Getty Images

Down-to-earth Kate usually keeps a low profile, according to Amaia. "She usually comes alone and although we show her everything we have in the size she needs, she usually knows what she wants. She's very decisive but she does let us make suggestions, and sometimes she buys things she wouldn't have picked up. She's very charming, very normal and very sweet."

Prince William's wife has even gotten her family in the habit of going to the store. "Her sister [Pippa Middleton] and her mom have also been back a few times to buy things for their nephew and niece and grandson, but at separate times."

The last time Kate paid a visit to Amaia Kids was when she was heavily pregnant with Princess Charlotte. "Three weeks before the princess was born, she came in and bought three cardigans, three shirts, two pairs of shorts and long socks," added Amaia.

Prince George, in Amaia Kids, has proved the perfect model for the brand Photo: Getty Images

The Spanish businesswoman currently lives in London with her Parisian husband and three children.